Plastic closures with tamper proof bands are well known in the prior art. In general, the lower portion of the closure skirt locks around a circumferential bead projecting from the outside surface of the container wall, just below the rim. The lower part of the skirt, below the protruding container bead, forms a tamper proof band which must be removed before the closure may be removed. Many different designs have been developed for permitting easy removal of the tamper proof band. Typically, the skirt is weakened by score lines on which the band may be torn away. Further, a tab is usually provided which the user may grasp to begin pulling the tamper proof band from the remainder of the closure. To make the tab accessible, the prior art has variously employed such methods as perforating an area around the tab, thickening the skirt walls near the tab, and forming an enlarged tab extending below the bottom of the skirt.
For example, U.S. Pat. No. 3,856,171 to Rossi discloses a tab partially cut away from the skirt and connected by a plurality of frangible strips, and a thickened skirt wall near the tab. U.S. Pat. No. 3,753,511 to Ruch discloses a similar band and tab, with a weakening score line formed on the outside of the skirt. While such prior art devices may be completely effective, the means employed to form the tab or frangible strip have been relatively expensive, and have used a greater amount of material than necessary. A more easily manufactured tamper proof closure, using a minimum amount of material, without loss of convenience in use is deemed desirable.